[TheDopp]

breaks the map balance

In all the times I've seen demos jump the rocks I've never seen it sway the outcome of the map. The only way it upsets the balance is if you're a really good demo that can jump over the wall, with the caber in hand, all the way to the final point once A and B are capped, and destroy everyone on the point with the caber.
Or you could huntspam and be more of an effect on balance.
Demo jumping displacements in other maps can change balance more than in Degroot (as I've mentioned previously).